Definition of Life

The best definition I heard was given by John Maynard Smith. A living
thing must a physical dissipative structure having the following
characteristics:
- Variation
- Reproduction
- Heredity
This definition excludes fire, vortexes, planets, replicating clay crystals,
priests and cellular automata. It includes, however, free replicating
informational molecules such as nucleic acids, which is pretty neat.
Julian Blanc